Link structures that can be linked together to form a rigid structure are well known in the art. Structures of this kind may be used to form a platform to elevate a person or equipment, to form a bridge to permit a user to pass over an obstacle, or to form a dock. Additionally, such structures have been used in space applications to extend a flexible sheet of material or to form a tower as a structure in space. See U.S. Pat. Nos. 2,661,082, 3,397,546, 4,024,595, 4,089,147, and 4,237,662.
Retractable towers of this kind may be further utilized as a portable telecommunications tower, wherein various sites can be tested without constructing a costly test tower at a location to discover it was not effective for the intended purpose. Retractable towers may also be used as temporary lighting systems for sporting events, emergencies, or on ships. Other applications may also be present in a variety of other fields and a variety of other situations.
The formation of retractable columns has been previously described. U.S. Pat. No. 4,920,710 to David L. Paine previously described a retractable support column for use in lifting and suspending overhead structures, which is herein incorporated by reference for everything it discloses. The structures that were formed using this apparatus and method, however, were subject to poor interconnection of the tower sections. The poor connection of the sides of the tower was caused in part by poor alignment of the section chains, and through the hooks, as the sides were raised. Poor alignment of the adjacent sections resulted in a poorly constructed tower; when a large amount of stress was placed on the poorly aligned tower, it sometimes resulted in the shearing of the pins holding the tower. The shearing of the pins resulted in a low structural integrity for the tower. These problems increased the difficulty in using tower systems of this type and also increased safety concerns and dangers.
Accordingly, there is a need for an improved retractable tower structure that provides greater structural integrity. There is a further need for a retractable tower which is more reliable, which provides a sturdier tower under adverse conditions, and which increases the load bearing characteristics of towers.